1. Field of the Invention
The invention relates to a wireless microphone, more particularly to a wireless microphone having a charger circuit and a transmitter circuit that share a common conductor pair.
2. Description of the Related Art
A conventional wireless microphone includes a transmitter circuit for outputting a microphone pick-up signal, and a charger circuit for charging an internal battery unit. In the conventional wireless microphone, because an antenna for the transmitter circuit and a conductor pair for the charger circuit are separate, the size of a circuit board in a housing of the wireless microphone is undesirably large, which increases the weight and which has an adverse affect on the portability of the wireless microphone.
Therefore, the object of the present invention is to provide a wireless microphone having a charger circuit and a transmitter circuit that share a common conductor pair so as to overcome the aforesaid drawbacks of the prior art.
According to the present invention, a wireless microphone comprises a housing, a circuit board mounted in the housing, a common conductor pair mounted on the circuit board, a charger circuit, a transmitter circuit, first and second impedance coils, and first and second isolation capacitors. The common conductor pair includes first and second conductors, each of which has a charging end and a connecting end. The charger circuit has a grounded first power terminal and a second power terminal. The transmitter circuit has a grounded first signal terminal and a second signal terminal. The first impedance coil has a grounded first coil terminal and a second coil terminal connected to the connecting end of the first conductor. The second impedance coil has a first coil terminal connected to the second power terminal, and a second coil terminal connected to the connecting end of the second conductor. The first isolation capacitor has a first capacitor terminal connected to the second signal terminal, and a second capacitor terminal connected to the connecting end of the second conductor. The second isolation capacitor is connected across the first and second conductors.
Therefore, when a direct current power signal is supplied to the charging ends of the first and second conductors, the power signal will be prevented from reaching the transmitter circuit by the first isolation capacitor and will be directed to the charger circuit by the second impedance coil.
Moreover, when the transmitter circuit outputs a microphone pick-up signal for transmission, the microphone pick-up signal will be prevented from reaching the charger circuit by the first and second impedance coils and will be directed to the first and second conductors through the first and second isolation capacitors for wireless transmission by the first and second conductors.